Fixed-free-reed electronic piano with electrodynamic translating means controlling the odd and even partialfrequency components



Nov. 2, 1965 B. F. MIESSNER 3,215,766

FIXED-FREE-REED ELECTRONIC PIANO WITH ELECTRODYNAMIC TRANSLATING MEANSCONTROLLING THE ODD AND EVEN PARTIAL-FREQUENCY COMPONENTS Filed Dec. 16,1964 2 Sheets-Sheet 1 A TTO/P/VEV s 3L0 1 x JINVENTOR.

Nov. 2, 1965 B. F. MIESSNER 3,215,766

FIXED-FREE- EED ELECTRONIC PIANO WI ELECTRODYNAMIC TRANSL NG OLLING THEODD AND MEA CO EVEN TIAL-FREQ CY COMPO TS Filed Dec. l 4 Sheets-Sheet 2BENJA IN F. M/ESSNER A T TORNE V United States Patent FIXED-FREE-REEDELECTRONIC PIANO WITH ELECTRODYNAMIC TRANSLATING MEANS CONTROLLING THEODD AND EVEN PARTIAL- FREQUENCY COMPONENTS Benjamin F. Miessner, 680 NE.105th St., Miami Shores, Fla. Filed Dec. 16, 1964, Ser. No. 418,716 15Claims. (Cl. 841.14)

This invention relates to an electronic piano, and more specifically tosuch a piano of the type wherein electric oscillations are translatedfrom the decadent free vibrations of fixed-free reeds which arerespectively provided for the several note-s of the pianos scale. As toeach reed the vibration of importance is its first-partial orfundamental vibration; in the translation of the electric oscillationsfrom that vibration there are introduced into those oscillationsmultiple-frequency oscillation components harmonically related to thatvibration, thereby to achieve pianistic tonal quality. Excitation and/or translation of upper-partial vibrations of the reed not harmonicallyrelated to its fundamental vibration is or are contemplated to beminimized or avoided; techniques for this purpose, being elsewheredisclosed or otherwise known, are not specially dealt with herein.

An important aspect of the present invention concerns the means employedfor the translation above referred to. In a number of earlier patentsissued on applications of mine I have shown electrostatic, orcapacitative, translating means which, in order to perform the functionof introducing the multiple-frequency oscillation compo nents, has beenpositioned so as to be swept past by the reed in at least itshigher-amplitude vibrations. This structure has the advantage of greatsimplicity. But it produces in the translated oscillations an electricwavefront of the same polarity each time the reed passes it, whicheverbe the direction of that passage; thus were that means to have beencentered with respect to the reeds vibratory swing (i.e. aligned withthe reeds rest position) the oscillations would have been of fundamentalfrequency double that of the reed, and would have contained harmonicpartials restricted to even-numbered multiples of the reed frequency.

To avoid this obviously undesirable effect those disclosures have shownthe electrostatic translating means slightly decentered with respect tothe reeds vibratory swing (i.e. displaced from alignment with the reedsrest position), and this has of course resulted in the appearance in thetranslated oscillations of components corresponding to the fundamentalfrequency of the reed vibration and to odd-numbered multiples thereof.Each of these, however, is of small amplitude at large amplitudes ofreed vibration, and actually increases as the vibrational amplitudedecays from those large amplitudes to an intermediate one; this not onlyresults in an excessive shift of harmonic structure in the earlyportions of a louder tone but also, because the fundamental is ofespecial importance in the impression created by the tone, renders thelouder tones organesque rather than percussive or pianistic incharacter. Moreover in the later portions of the tones themultiple-frequency components decay at an excessive rate, and each tonetends to end with little excepting fundamental-which is in itselfabnormal, and furthermore in the case of very low-frequency tonesresults in an excessively rapid falling of the tone below the thresholdof audibility. These shortcomings, which constitute a significantblemish on the pianistic quality of the output tones, are the directresult of the fact that the simple electrostatic translating means abovereferred to translates wavefronts of the same polar- 3,215,766 PatentedNov. 2, 1965 ity in response to oppositely directed sweeps of the reed,and of the reliance on the abovementioned decentering (or displacing)expedient for the elicitation of the basically important fundamentalcomponent (as well as oddnumbered multiple-frequency components) of theoscillations.

I am aware that, among translating means which may be bidirectionallyswept past by the reed in each cycle of its higher-amplitude vibrationin order to achieve the introduction of multiple-frequency components,there are some which produce in the translated oscillations wavefrontsof opposite polarity in response to the oppositely directed sweeps ofthe reed. Thus for example in one earlier patent issued on anapplication of mine (No. 3,038,363, in which, see Sheet 9 of thedrawings) I among other things disclosed, for a fixed-free-reedelectronic piano, various electromagnetic translating means of whichthose shown in FIGURES 49, 50, 51, 53 and 54 are bidirectionally sweptpast by the reed in the above stated manner and do introducemultiple-frequency components-among which in turn that one shown in FIG-URE 53, if used with longitudinal magnetization of the reeds (asalternatively disclosed in column 31 of the patent), will translateoscillations containing the fundamental and odd-numberedmultiple-frequency components. (The others of the several figures abovereferred to will produce only double-frequency and other evennumberedpartials.) I have also become aware, however, that the oscillationstranslated by that FIGURE 53 structure (with longitudinal reedmagnetization) from the fundamental reed vibration wholly fail toinclude any components whatever at even-numbered multiples of the reedsfundamental vibrational frequency. The result of this failure is anoutput tone which, while not suffering the shortcomings mentioned in thepreceding paragraph, sufiers another serious shortcoming: theunpianisticfhollowness characteristic of tones which contain onlyoddtions of components at even-numbered multiples of the reedsfundamental frequencyand will do so in a manner well suited to theachievement of a pianistic output-tone quality. This is not without aconsiderable element of surprise, in view of the fact that with theother type of translating means (first above discussed) it was that samedecentering (or displacing) of the translating means which:

served to introduce components at odd-numbered multiples of the reedsvibrational frequency. I have, furthermore, found it to be a procedurewhich does not suffer from any shortcoming comparable to theabove-discussed limitation on the amplitude of fundamental (andodd-numbered multiple-frequency) components which can be added in thecase of the other type of translating means. (While I do not undertaketo present a complete explanation for this observation, it appears to meon analysis to be related to the proposition that both the presence andthe rate of change of the fundamental component in the output tone areof elementaryjmportance in pianistic quality, cannot be compromised, andcan only be assured as a result of some basic, rather than a secondary,aspect of the structurewhile the presence and rate of change of theeven-numbered multiple-frequency components, while qualitativelyimportant, are not of great quantitative, criticality. It may well alsoand independently be due to the facts that the introduction ofeven-numbered multiple-frequency components by decentering involves adesymmetricalizing of the waveform and that this geometrically increasesat the lower vibrational amplitudes at which the degree ofmultiple-frequency introduction is inherently the least, so that aninherent compensation-quite absent in the converse caseis automaticallyachieved.)

In the above-discussed aspect the invention comprises the use with thefixed-free reed of an electronic piano of an electric translating means,having a portion located adjacent to and influenced by an edge portionof the reed and bidirectionally swept past by the reed in each cycle ofthe reeds higher-amplitude vibration, for translating from the reedvibrations electric oscillations comprising wavefronts of respectivelyopposite polarity in response to the oppositely directed sweeps of thereed, whereby the oscillations are caused to contain components of thefundamental frequency of the reed vibration and odd-numbered multiplesthereof, that translating-device portion being displaced from alignmentwith the rest position of the reed whereby to cause those oscillationsalso to contain components of even-numbered multiples of the reedsfundamental frequency.

In another aspect the invention concerns a preferred translating meansof the type first mentioned in the preceding paragraph (i.e. of the typewhich translates oscillations comprising wavefronts of respectivelyopposite polarity in response to the oppositely directed sweeps of thereed). I have found especially favorable, from the viewpoints both ofsimplicity and effectiveness, an electrodynamic form of translatingmeans comprising an electrical' conductor adjacent a free edge portionof the reed and bidirectionally swept past by that edge portion in eachcycle of the reeds higher-amplitude vibration, means creating a magneticfield transverse to the conductor in the region adjacent that edgeportion, an electrically conductive loop in which the conductor isserially included, and output means responsive to the current generatedin the loop by the vibrating reedthe reed comprising magnetic, if notalso magnetized, material.

Subordinately as to the aspect last stated, the abovementioned edgeportion of the reed may be the reeds free end. The field-creating meansmay be a magnet fonming the free-end portion of the reed. Alternativelythe field-creating means may comprise a magnet disposed on the oppositeside of the conductor from the free end of the reed; in that case, toavoid undesirable reaction from the magnet on the reed vibrations in thecase of a lowerfrequency reed, the surface of the magnet facing the freeend of the reed may be arcuate and substantially equispaced from thatfree end as the reed vibrates. Still alternatively the reed may be ofmagnetizable material and may be magnetized to itself constitute thefieldcreating means; in that case, to achieve good magnetization withoutrisk of reed breakage at or near its fixed end, the reed may be ofharder material in its free-end portion and may there be magnetized. Tomaximize the introduction of multiple-frequency components throughoutthe scale in spite of progressively diminishing maximum vibrationalamplitudes toward the upper end of the scale, the thickness of theconductor, and of the magnets forming the free-end portions of the reeds(when employed), may be progressively reduced toward that upper end.

Still another aspect of the invention is related to the first. It may bedesired very precisely to predetermine the general balance betweenevenand odd-numbered partials in the output oscillations of the system;on the other hand it may be desired from time to time to vary thatbalance for deliberate variation of tonal effects. To achieve either ofthose and/or other possible objectives the invention optionallycontemplates the use, with the reed, of two translating means each ofthe type (above referred to) which translates from the reed vibrationselectric oscillations comprising wavefronts of respectively oppositepolarity in response to the oppositely directed higher-amplitude sweepsof the reed, the respective portions of-those two means adjacent to andinfluenced by the edge portion of the reed being spaced from each otherin the direction of the reed vibration, together with means connectedwith the two translating means for combining oscillations from each in aselected relationship. Typically, though not necessarily limitatively,the abovementioned portion of one (of course, one only) of thosetranslating means may be aligned with the rest position of the reed.

The aspect set forth in the preceding paragraph will ordinarily beembodied in a structure wherein each of the respective portions of thetwo translating means adjacent to and influenced by an edge portion ofthe reed is bidirectionally swept past by the reed in each cycle of thereeds higher-amplitude vibration but at least one of those respectiveportions is not thus swept past during useful lower-amplitude vibrationof the reed. In such an embodiment that aspect does not necessarilydepend for its novelty on the limitation that either or both of thetranslating means be of the type which translates from the reedvibration electric oscillations comprising Wavefronts of respectivelyopposite polarity in response to the oppositely directed sweeps of thereed; itmay accordingly be re-stated without that limitation as another,though related, aspect.

Various objects of the invention have been made apparent by theforegoing brief description. Allied and other objects will be apparentfrom the following detailed description and the appended claims.

General objects are the provision of an improved electronic piano of thetype wherein electric oscillations are translated from the decadent freevibrations of fixedfree reeds, and the provision of improved translatingmeans for such a piano. Another object is the provision of an improvedreedor vibrator-exciting action.

In the detailed description of the invention reference is had to theaccompanying drawings, in which FIGURE 1 is a bottom plan view of thereed-and-translating-means assembly of an electronic piano according tothe invention, together with a schematic showing of certain electricalapparatus associated therewith;

FIGURE 2 is a vertical cross-sectional view taken along the line 2-2 ofFIGURE 1 (the line 11 in FIG- URE 2 indicating the plane along whichFIGURE 1 is taken) and also fractionally illustrating a reed-excitinghammer action for the reed appearing in FIGURE 2;

FIGURE 3 is a vertical cross-sectional view taken along the line 3-3 ofFIGURE 1;

FIGURE 3a is an enlarged view of a small portion of FIGURE 3;

FIGURE 4 is a vertical cross-sectional view taken along the line 44 ofFIGURE 1;

FIGURE 4a is an enlarged view of a small portion of FIGURE 4;

FIGURE 5 is a vertical cross-sectional view taken along the line 55 ofFIGURE 1;

FIGURE 6 is a vertical cross-sectional view taken along the line 6-6 ofFIGURE 1;

FIGURE 7 is a View generally similar to FIGURE 4 but illustrating amodification in respect of the magnetic field-creating means;

FIGURE 8 is a view generally similar to FIGURE 4 but illustrating afurther modification of the magnetic field-creating means; and FIGURE 9is a plan view alternative to FIGURE 1 illustrating a modification ofthe layout of the reeds and reed-supporting frames.

In the description of the electronic piano shown in FIGURES 1 through 6of the drawings reference may first conveniently be had to FIGURE 2,which is a vertical cross section through the lowest-frequency reed RHerem there will be seen a generally L-cross-sectioned frame 1 ofrelatively hard metal (such as a suitable aluminum alloy) of which theshorter leg 2 is a downhanging vertical one through which there passes ahorizontal hole 7. The fixed end of the reed K, may be fitted into l alongitudinal slot 8 formed in one end portion of a generally cylindricalplug 9 of deformable metal, and that plug may then be axiallyforce-fitted (its other end first) into the hole 7 to provide a rigidclamping of the reeds fixed end to the frame 1. The longer leg 3 of theframe extends forwardly above the reed R typically to a little furtherthan the reed itself extends; to its end face there may be secured adownhanging member 4 of non-magnetic and preferably insulating material,which may be used as a support for elements hereinafter de scribed.

Below and to the rear of the frame 1 there may be pivotally mounted to asuitable support the butt 18 of a hammer 10 whose shank 17 extends fromthe butt and at its free extremity carries a hollow cylindrical hammerhead 11 which is directed upwardly toward the reed and at its upper endcarries a reed-contacting pad 12 hereinafter further referred to. Thehammer may be rocked about its pivotal mounting, so that the pad willstrike the reed to set the reed into decadent vibration, by aconventional piano key 20 coupled to the hammer butt 18 by an elongatedcapstan 21. The geometry of the system may be so arranged that the meanpoint of strik ing of the reed by the pad 12 is at approximatelyonequarter of the length of the reed away from the plug 9.

Reference being had to FIGURE 1 (in which one looks upwardly at frameand reeds) it will be seen that the frame 1 is laterally extended tocarry a number of reedsfor example thirty-one, of which thelowest-frequerrcy reed is R; and the highest frequency reed R In thislateral extension the thickness of the vertical leg 2 is tapered in alinearly increasing manner and the length of the horizontal leg 3 istapered in a linearly decreasing manner; this, done in view of theprogressively diminishing lengths of the reeds for successively higherfrequencies, is carried out with the forward surface of the vertical leg2 and the forward edge of the horizontal leg 3 each angled with respectto the front of the piano, and with the mean points of striking of theseveral reeds by their respective hammers forming a straight line(designated as L) parallel to that front.

For a succeeding group of reeds, typically the next twenty-four, theremay be provided a second frame having vertical leg 2a and horizontal leg3a, the thickness of the former and the length of the latter again beinglinearly tapered but in reduced degree. For a further succeeding groupof reeds, typically the next eighteen, there may be provided a thirdframe having Vertical leg 2b and horizontal leg 3b, the thickness of theformer and the length of the latter again being linearly tapered but infurther reduced degree. And for a final group of reeds, typically thelast twelve, there may be provided a fourth frame having vertical leg 20and horizontal leg 30, the thickness of the former and the length of thelatter being still again linearly tapered but in still further reduceddegree. Downhanging members 4a, 4b and 4c, corresponding to member 4,may be provided for the second, third and fourth frames respectively.

Each of the reeds (K; through R carried by the first frame and each ofthose (R through R carried by the second frame is shown as having a freeend portion comprising a magnet which is magnetized longitudinally ofthe reed. These magnets may be of the ceramic variety; they may forexample first be copper-plated, and then butt-soldered to the end of thereed proper. All these magnets may for example have a width (i.e.dimension transverse of the reed) of about and a thickness of about ,4(contrasting with typical reed-proper width and thickness of about A3"and & respectively); Those magnets which are comprised in the firstthirteen reeds may for example have a length (ie dimension longitudinalof the reed) of about A", those comprised in the next nine reeds alength of about A3", and those comprised in the remaining ones ga e 6 ofthe magnet-comprising reeds a length of about 6 Tuning of themagnet-comprising reeds may be accomplished by the incorporation ofappropriate amounts of extra solder secured to the reed, preferably atthe region of juncture of the magnet with the reed proper. Thus withrespect to the reeds carried by the first frame, FIGURE 1 by way ofexample shows at that region on reed R.,, a substantial fillet R; ofextra solder, but no substantial extra solder on reed R at that regionon reed R a substantial fillet F of extra solder, but no substantialextra solder on reed R and at that region on reed R a substantial filletF of extra solder, but no substantial extra solder on reed R On thereeds carried by the second frame no substantial extra solder isactually illustrated, as the progressive lengths of its reeds are nearlyenough correct to avoid the need for substantial extra amounts.

Each of the magnets comprised in the reeds R through R is designated bythe letter M followed by the same numerical subscript as used for therespective reed.

The reeds carried by the third and fourth frames are shown as simplereeds, not comprising any magnets; they are, however, of magneticmaterial (as the reeds proper in the case of the earlier-described reedspreferably also are). In the case of each of those two frames theprogressive lengths of its reeds are nearly enough correct to avoid theneed for major tuning expedients, and they may be tuned by the usualfinetuning techniques. It may also be noted that the lowest-frequencyreed (R carried by the third frame is shown as somewhat longer than thehighest-frequency reed (R carried by the second frame in view of itsbeing the first reed without the loading effect of a contained magnet.

FIGURE 2, illustrating the reed R and the exciting means therefor, hasalready been referred to. FIGURES 3, 4, 5 and 6 respectively illustratethe reeds R R R and R For simplicity FIGURES 3 and 5 omit any showing ofexciting means, and FIGURES 4 and 6 show such means only fractionally;it will of course be understood, however, that a respectivekey-and-hammer action will be provided for each reed of the piano, inaccordance with conventional practice.

The reeds and their mounting and their exciting means having been thusdescribed, attention may be directed to the preferred translating meansaccording to the inventions second aspect introductorily stated above.

Adjacent a free edge portion of the reedtypically the reeds free cndIplace an electrical conductor bidirectionally swept past by that edgeportion in each cycle of (at least) the higher-amplitude vibration ofthe reed; such a conductor is shown in FIGURES 1 through 6 as 30, lyingin the plane of the reeds, supported in any convenient manner or manners(not illustrated) to members 4 and 4a and in manner hereinafterdescribed to members 4b and 4c, and formed into close adjacency to thefree end of each reed. I provide an electrically conductive loop inwhich that conductor is serially included; FIGURE 1 shows this loop asformed by the conductor 30 with the one or fewturn primary 31 of atransformer 33, the portion of frame 3c intervening between connectingscrews 50 and 6c, the conductive jumper 290, the portion of frame 3bintervening between connecting screws 5b and 6b, the conductive jumper2915, the portion of frame 3a intervening between screws 5a and 6a, theconductive jumper 29a, and the portion of frame 3 intervening be tweenconnecting screws 5 and 6 (at which latter the conductor 30 may beconsidered as beginning). And with respect to each reed I provide meanscreating a magnetic field transverse to the conductor in the regionadjacent the reeds edge portion (e.g. free end); with respect to each ofthe reeds carried by the first and second frames this means consists inthe respective magnet already described as comprised in that reed.

With respect to each of the reeds carried by the third and fourth framesthe field-creating means is shown in FIGURES 1, and 6, as consisting ofa magnet disposed on the opposite side (e.g. forwardly) of the conductor30 from the free end of the respective reed and magnetized in adirection longitudinal of the reed. For each such reed the respectivemagnet is designated by the letter M together with the same numericalsubscript as used in the designation of that reed. Each magnet may besecured in any convenient manner to the bottom of the downhanging member4b or 4c (as the case may be), and may in turn form a means supportingthe conductor 30. By way of example these magnets are shown as eachapproximately long and A" wide, with those carried on memlber 417 (seeFIGURE 5) each about A" thick and those carried on member 4c (see FIGURE6) each about /8" thick.

It will be understood that, in the case either of the reedincludedmagnet or of the stationary separate magnet, a field is createdtransverse to the conductor 30 and longitudinal of the reed. In the caseof each of the magnet-including reeds this field will pass through theconductor 30 without concentration; in the case of each of the otherreeds it will converge, in passing through the conductor, to concentrateitself in the free end of the reed in view of the magnetic nature andhence low reluctance of the reed material. In either case the vibrationof the reed will cause the lines of force (which make up the field) tocut the conductor 30, the effect of which is to induce an oscillatorycurrent in the conductor and thus in the abovedescribed loop in which itis included.

The electric oscillations of which that oscillatory current consists areof course translated from the reeds vibration (which will here beassumed to be essentially only at its fundamental frequency). Becausethe direction of instantaneous current flow in the conductor 30 dependson the direction in which the magnetic field cuts the conductor, thewavefronts respectively produced in the translated oscillations by theup and down sweeps of the reed will be of opposite polarities, with theresult that the translated oscillations will contain a substantialcomponent at the fundamental frequency of the reed vibration. Becausethe reed sweeps by the conductor 30at higher vibrational amplitudes,very rapidly and through two very restricted portions only of itscyclethere will be introduced into the oscillations components atfrequencies which are multiples of that fundamental frequency. But, withthe conductor 30 in its described and illustrated position of alignmentwith the rest position of the reed so that it is centered with respectto the reeds vibratory swing, those multiple-frequency components willbe at odd-numbered multiples onlyusually a distinct disadvantage ofwhich mention was made above.

I have found that if instead of the conductor 3t) there be employed aconductor 40 somewhat decentered with respect to that swing, ordisplaced from alignment with the rest position of the reed, componentsat even-numbered as well as at odd-numbered multiples will beintroduced.

Such a conduct-or 40 will be seen in FIGURES 1 through 6, positionedsomewhat above but otherwise similarly to the conductor 30. It isserially included in a loop which, in addition to the conductor 40,includes the oneor few-turn primary 41 of a transformer 43 and aconductor 39 leading from that primary to the lefthand end of the piano(where the conductor 40 may be considered to start) and there mergingwith that conductor 40.

It may be mentioned that in order to acco-modate the showing of theconductor 30-whose presence jointly with the conductor 40 iscontemplated according to aspects of the invention yet to be detaileddescribedthe conductor 40 has beenillustrated in a higher poistion thanthe preferred one which it would occupy if the conductor 30 were notpresent. In general, that preferred position of the conductor 40' whenused alone would be one displaced from alignment with the reeds restposition by a fraction only of the degree by which that conductor hasbeen shown as displaced in the figures.

With the conductor 40 occupying its preferred position as justdescribed, there are produced in it oscillations representing excellentpianistic quality, with thoroughly satisfactory even-numbered (as wellas odd-numbered) multiple-frequency components and without any of thedeficiencies as to fundamental component which were introductorilydescribed.

The separate magnets shown in connection with the reeds carried by thethird and fourth frames should in general be of thickness sufficient sothat the swing of any reed does not carry its free end appreciably aboveor below the respective magnet. Accordingly for the highestfrequencyreeds (whose maximum swing is small) the use of a thin magnet as inFIGURE 6 is permissible, while for somewhat lower-frequency reeds (whoseswing is greater) a somewhat thicker magnet as in FIGURE 5 is calledfor.

The separate-magnet structure may be carried on downwardly in the scale,but then not only is a quite considerable thickness required in order toobey the specification of the preceding paragraph, but also anotherphenomenon manifests itself and requires attention-Le. a pull of themagnet on the reed which, although the reed is still opposite the magnetto be pulled, diminishes at the extreme swings of the reed because ofthe arcuate nature of the locus of the reeds free end. This phenomenonwill result (just as would an appreciable overshooting of the magnet bythe reed) in a shifting effect on thereeds vibrational frequency asbetween highand low-amplitude vibration, and is quite intolerable.Accordingly when it is desired to utilize the separate magnet for alower-frequency reed it is desirable not onlyto make it sufficientlythick, but also to make its reed-facing surface arcuate andsubstantially equispaced from the free end of the reed as the reedvibrates. This has been illustrated in FIGURE 7, for a reed R not itselfcontaining any magnet but otherwise of a length corresponding to that oficed R (shown in FIGURE 4), by the magnet M which obeys thespecifications of the preceding sentence.

There is an alternative, to both the magnet comprised in the reed andthe separate magnet, which may be employed at any or all regions of thescale; this comprises a reed of magetizable material magnetized toitself constitute the field-creating means. I have found, however, thatit is desirable to embody this in a particular manner, lest the hardnesswhich is requisite for good magnetic retentivity result in too greatbrittleness of the reed at and near its fixed extremity and inconsequent propensity to reed breakage there. According to this manner Iform the reed of a material such as a relatively hard cobalt steel (e.g.having a Rockwell hardness of about 65 RC); I anneal the fixed-endapproximate half of the reed, but leave the other or free-end half atits normal hardness magnetizing (longitudinally) the latter half only.FIG- URE 8 illustrates as R a reed (otherwise similar to the reed R ofFIGURE 7) treated in this manner.

In connection with the introduction of multiple-frequency componentsinto the translated oscillations, I have observed that this is enhanced,especially in the middle and higher portions of the scale, by reducingthe thickness of the conductor 30 or 40 (or both when employed) and,when magnets form the free-end portions of the reed, the free-endthickness of those magnets, and that best results are achieved by makingsuch thickness reductions progressive with increasing frequency.Accordingly in FIGURES 2 through 6 it will be seen that the thicknessesof the conductors 30 and 40 have been progressively reduced, and inFIGURES 2 through 4 that the reed-contained magnets have beenprogressively bevelled to result 9 in a progressive reduction of theirfree-end thicknesses (the enlarged FIGURES 3a and 4a facilitating anobservation of the latter).

It is also to be observed that when the conductors 30 and 40 are jointlyused it is desirable progressively to reduce the inter-center spacingsof those conductors with progressively higher reed frequency. Thistechnique, illustrated in FIGURES 2 through 6, is of course facilitatedby the progressive reductions of the thicknesses of those conductors,just mentioned.

Each loop which is employed is provided with output means responsive tothe current generated in that loop by the vibrating reeds. Accordinglyeach of the transformers 33 and 43 has been shown as provided with amany-turn secondary (32 or 42), which constitute such means for therespective loops.

Attention may now be turned to the joint use of the two conductors 30and 40. It has already been pointed out that the conductor 30, alignedwith the rest positions of the reeds, will not introduce anyeven-numbered multiplefrequency components into the translatedoscillations; on the other hand the conductor 40, being substantiallydisplaced from such alignment, will tend to introduce a very ample, ifnot excessive, quantity of such components. Advantage may be taken ofthese opposite characteristics, for such purposes as relatively precisepredetermination of the general balance between evenand odd-numberedmultiple-frequency components or deliberate variation from time to timeof that balance for special tonal effects, by the joint use of the twoconductors together with means for combining the oscillation outputstherefrom in one or another selected relationship. To provide such meansthe secondaries 32 and 42 may be connected across respectivepotentiometers 34 and 44 which may have respective fixed center-taps 35and connected together, and which have respective variable contacts 36and 46 (each for example movable over the whole potentiometer); thesevariable contacts may form the output terminals of the translatingsystem, across which terminals will appear oscillations from each of thetwo translating means combined in a relationship selectedboth as toamplitude and as to phase-by the adjustments of the contacts 36 and 46.From these terminals (or directly from the transformer secondary if onlyone of the translating means and thus one transformer be employed) theoscillations may typically be applied to the input of an electronicamplifier 50, whose amplified output in turn feeds a loudspeaker orother electro-acoustic translating device 51.

It will be appreciated that when both the conductors 30 and 40 areemployed, together with such means as the potentiometers 34 and 44,there are associated with each reed two translating means each of thetype which translates from the reed vibrations electric oscillationscomprising wavefronts of respectively opposite polarities in response tothe oppositely directed higher-amplitude sweeps of the reed, and thatthe reed-influenced portions of those two means are spaced from eachother in the direction of reed vibration. From another point of viewthere are then associated with each reed two translating means eachbidirectionally swept past by the reed in each cycle of-itshigher-amplitude vibration but of which at least one is not swept pastduring useful lower-amplitude vibrations of the reed. The structureaccording to either of the two preceding sentences I have found of greatvalue, in a decadent-tone instrument such as an electronic piano, forsuch purposes as dealt with in the preceding paragraph.

Attention may be re-directed to the reed-exciting action shown in FIGURE2 and briefly described above as being provided for each of the severalreeds. In it there may be incorporated techniques broadly similar tothose disclosed in Patent No. 2,271,460 heretofore issued on anapplication of mine, including in particular the partial filling of thehollow cylindrical hammer head 11 with individual solid particles 13forwhich I have now found metallic shot to be an excellent choice. Upondepression of the front end of the key 20 the hammer 10 will bepropelled upwardly toward the reed; this propulsion will go on until therear end of the key has been brought upwardly into impingement againstthe adjustable up-stop 23, at which time the hammer head 11 and itsreed-striking pad will have been brought upwardly to such a position asis indicated in either of FIGURES 4 and 6. Further propulsion of thehammer and the shot 13 contained in the head 11 is then terminated, butboth will move on under the influence of momentum so that the pad 12strikes the reed; there is then foreclosed further upward movement ofthe head 11, which instead rebounds downwardly, but the contained shot13 may and does continue to move upwardly-the shot impinging against theupper-end inner surface of the rebounding head 11 and largelyneutralizing or absorbing the energy of its rebound. Furthermore whenthe butt 18 of the rebounding hammer impinges on the top of thestill-raised capstan 21, at which time it and the hammer tend to executea re-bound, the shot 13, still elevated within the head 11, flies ondownwardly into impingement against the lower-end inner surface of thehead and neutralizes or absorbs the energy of the re-rebound.

In the present structure the hammer head is propelled at many times asgreat a velocity as in the disclosure of the patent, and I have foundthat problems arise in connection with the timing or phasing of theneutralizing or energy-absorbing impacts of the shot against the endinner surfaces of the head 11 (particularly the upper inner surface).These problems I have found it possible to solve by progressivelyreducing the stroke' of the shot 13 for progressively higher-frequencyreeds (with which the speed of rebound of course becomes progressivelygreater). This I have illustrated in FIGURES 4 and 6, taken incomparison with FIGURE 2. Thus in FIGURE 4 I show a plug 14 of moderatethickness underneath the shot 13 and serving to reduce the free lengthof the space within the hollow hammer head 11 of that figure, while inFIGURE 6 I show a plug 14" of substantially greater thickness in asimilar position and serving to reduce still further the free length ofthe space within the hollow hammer head 11" of that figure.

In connection with the hammers I may point out another technique which Ihave found of value in setting the reeds into decadent vibration bothefliciently and principally at their fundamental frequencies. This isthe use of reed-contacting pads (typically of medium felt) which for thelowest-frequency reeds are of relatively substantial lengthlongitudinally of the reed, but which are progressively reduced in suchlength for progressively higher-frequency reeds, as seen in thecomparison of pads 12, 12' and 12" in FIGURES 2, 4 and 6 respectively.This technique may be supplemented by that of some progressivediminution of thickness of those pads, also illustrated in thosefigures.

An electronic piano with the translating means above disclosed may bevoiced, or adjusted for proper relative tone amplitudes from its severalreeds when correspondingly excited, by adjustment of the separationbetween the conductor or conductors (30 and/or 40) and the vibrationallocus of the end of each reed-it being understood that maximum toneamplitude from any reed for a given vibratory amplitude of that reed isachieved with the closest possible such spacing which does not interferewith the reed vibration. (This spacing also has some effect on thedegree of introduction of multiple-frequency components into thetranslated oscillations, and in order not unnecessarily to reduce thatdegree excessive spacings should be avoided.) Voicing in the manner justindicated can readily be employed to adjust out or eliminate any breaksin the tone amplitudes as between successive reeds which are providedwith quantitatively or qualitatively ditferent field-creating means(such as the successive reeds R -R or R -R or R R It may be pointed outthat in the figures the separation discussed in the preceding paragraphhas been exaggerated in order clearly to show the separate parts;ordinarily it will be of the order of a few thousandths of an inch only.Thus the relationship of the conductor or conductors 30 and/or 40 to thereeds free edge portion (e.g. end) is one of close adjacency; it is alsoone of immediate adjacency-Le. there is no object intervening betweenthe conductor or conductors and the reeds free edge portion.

In the layout according to FIGURE 1 there is a necessity to angle theconductors 30 and 40 between successive reeds. To avoid such anecessity, at least within each one of the several frames, recourse maybe had to the slightly modified layout of FIGURE 9. Herein each of thefour frames 1, 1a, 1b and has been replaced by a frame (61, 61a, 61b or610) modified as by rocking the quardilateral representing its outline,so as to increase two and decrease two of its four angles-so that thefree ends of the reeds within that frame lie in a straight line which isat right angles to each of those reeds. The several frames are in turnso related to each other that the line L of striking of the severalreeds by their hammers is a straight one across the entire instrument,which results in some (but very slight) tie-alignments as between thefour lines respectively formed by the reed ends in the four frames. InFIGURE 9 the vertical legs or portions of the four frames are designatedas 62, 62a, 62b and 620, and the horizontal portions as 63, 63a, 63b and63c, respectively. For simplicity of the figure only a limited number ofreeds are shown, with little detail, and the magnets and conductors havebeen omitted.

While I have disclosed my invention in terms of particular embodimentsthereof it will be understood that I thereby intend no unnecessarylimitations. Modifications in many respects will be suggested by mydisclosure to those skilled in the art, and such modifications will notnecessarily constitute departures from the spirit of the invention orfrom its scope, which I undertake to define in the following claims.

I claim:

1. An electronic piano of the type wherein electric oscillations aretranslated from the decadent free vibration of a fixed-free reed andwherein multiple-frequency oscillation components harmonically relatedto that vibration are introduced in that translation into thoseoscillations, including in combination a fixed-free reed, means forsetting the reed into decadent vibration in the direction of itsthickness, and electric translating means, having a portion locatedadjacent to and influenced by a free edge portion of the reed andbidirectionally swept past by that edge portion in each cycle of thehigher-amplitude vibration of the reed, for translating from the reed'vibrations electric oscillations comprising wavefronts of respectivelyopposite polarities in response to the oppositely directed sweeps of thereed, whereby said oscillations are caused to contain components of thefundamental frequency of the reed vibration and odd-numbered multiplesthereof, said translating-means portion being displaced from alignmentwith the rest position of the reed whereby to cause said oscillationsalso to contain components of even-numbered multiples of saidfundamental frequency.

2. An electronic piano of the type wherein electric oscillations aretranslated from the decadent free vibration of a fixed-free reed andwherein multiple-frequency oscillation components harmonically relatedto that vibration are introduced in that translation into thoseoscillations, including in combination a fixed-free reed compris- :ingmagnetic material and vibratable in the direction of its thickness, anelectrical conductor passing along and in immediate adjacency to a freeedge portion of the reed and bidirectionally swept past by that edgeportion in each cycle of the higher-amplitude vibration of the reedmeans, creating in the immediate vicinity of said edge portion amagnetic field which when said conductor is swept past by the reedpasses transversely through said conductor along the plane of the reed,an electrically conductive loop in which said conductor is seriallyincluded, and output means responsive to the current generated in theloop by the vibrating reed.

3. The subject matter claimed in claim 2 wherein said edge portion isthe free end of the reed.

4. The subject matter claimed in claim 3 wherein the reed is of magneticmaterial and said field-creating means comprises a magnet disposed onthe opposite side of said conductor from said free end of the reed.

5. The subject matter claimed in claim 4 wherein the surface of saidmagnet facing said free end of the reed is arcuate and substantiallyequispaced from said free end of the reed as the reed vibrates.

6. The subject matter claimed in claim 2 wherein said field-creatingmeans is :a magnet forming the free-end portion only of the reed.

7. The subject matter claimed in claim 2 wherein the reed is ofmagnetizable material and is magnetized to itself said field-creatingmeans.

-8. The subject matter claimed in claim 2 wherein the free-end portionof the reed is of magnetizable material and is relatively hard and ismagnetized to constitute said field-creating means, and wherein thefixed-end portion of the reed is of relatively softer material.

9. The subject matter claimed in claim 2 further including a secondelectrical conductor, spaced from said firstrecited conductor in thedirection in which the reed vibrates, also adjacent said free-edgeportion and also bidirectionally swept past by that edge portion in eachcycle of the higher-amplitude vibration of the reed, a secondelectrically conductive loop in which said second conductor is seriallyincluded, second output means responsive to the current generated in thesecond loop by the vibrating reed, and means connected with said twooutput means, for combining oscillations from each in a selectedrelationship.

10. An electronic piano of the type wherein electric oscillations aretranslated from the decadent free vibrations of fixed-free reeds andwherein multiple-frequency oscillation components harmonically relatedto those vibrations are introduced in that translation into thoseoscillations, including in combination a series of progressively tunedfixed-free reeds each comprising magnetic material and vibratable in thedirection of its thickness, an electrical conductor passing along and inimmediate adjacency to a free edge portion of each of the reeds andbidirectionally swept past by that edge portion of each reed in eachcycle of the higher-amplitude vibration of that reed, means creating inthe immediate vicinity of said edge portion of each reed a magneticfield which when said conductor is swept past by that reed passestransversely through said conductor along the plane of that reed, anelectrically conductive loop in which said conductor is seriallyincluded, and output means responsive to the currents generated in theloop by the vibrating reeds.

11. The subject matter claimed in claim '10 wherein the thickness ofsaid conductor is progressively diminished in its portions adjacentprogressively higher-frequency reeds.

12. The subject matter claimed in claim 10 wherein said field-creatingmeans for each reed of said series is a respective magnet forming thefree-end portion of that reed, and wherein the free-end thicknesses ofsaid magnets in progressively higher-frequency reeds are progressivelydiminished.

13. The subject matter claimed in claim 12 wherein the thickness of saidconductor is progressively diminished in its portions adjacentprogressively higher-frequency reeds.

14. An electronic piano of the type wherein electric oscillations aretranslated from the decadent free vibration of a fixed-free reed andwherein multiple-frequency oscillation components harmonically relatedto that vibration are introduced in that translation into thoseoscillations, including in combination a fixed-free reed, means forsetting the reed into decadent vibration in the direction of itsthickness, two electric translating means, each having a portionadjacent to and influenced by a free edge portion of the reed and'bidirectionally swept past by that edge portion in each cycle of thehigher-amplitude vibration of the reed, each for translating from thereed vibrations electric oscillations comprising wavefronts ofrespectively opposite polarities in response to the oppositely directedsweeps oft-he reed, said portions of said two translating means beingspaced from each other in the direction of reed vibration, and meansconnected with said two translating means for combining oscillationsfrom each in a selected relationship.

15. An electronic piano of the type wherein electric oscillations aretranslated from the decadent free vibration of a fixed-free reed andwherein multiple-frequency oscillation components harmonically relatedto that vibration are introduced in that translation into thoseoscillations, including in combination a fixed-free reed, means forsetting the reed into decadent vibration in the direction of 20 itsthickness, two electric translating means each having a portion adjacentto and influenced by a free edge portion of the reed and bidirectionallyswept past by that edge portion in each cycle of the higher-amplitudevibration of the reed, said portions of said two translating means beingspaced from each other in the direction of reed vibration and at leastone of them being not swept past by said edge portion of the" reedduring useful lower-amplitude vibration of the reed, and means connectedwith said two translating means for combining oscillations from each ina selected relationship.

References Cited by the Examiner UNITED STATES PATENTS 2,581,963 1/52Langloys 841.15 X 2,704,957 3/55 Miessner 841.l5 2,881,651 4/59 Andersen84- l.14 2,901,936 9/59 Scherer et al 841.14 X 2,948,178 8/ 60 Jacobson84-1.04 3,038,363 6/62 Miessner 841.l4

ARTHUR GAUSS, Primary Examiner.

2. AN ELECTRONIC PIANO OF THE TYPE WHEREIN ELECTRIC OSCILLATIONS ARETRANSLATED FROM THE DECADENT FREE VIBRATION OF A FIXED-FREE REED ANDWHEREIN MULTIPLE-FREQUENCY OSCILLATIN COMPONENTS HARMONICALLY RELATED TOTHAT VIBRATION ARE INTRODUCED IN THAT TRANSLATION INTO THOSEOSCILLATIONS, ICNLUDING IN COMBINATION OF FIXED-FREE REED COMPRISINGMAGNETIC MATERIAL AND VIBRATABLE IN THE DIRECTION OF ITS THICKNESS, ANELECTRICAL CONDUCTOR PASSING ALONG AND IN IMMEDIATE ADJACENCY TO A FREEEDGE PORTION OF THE REED AND BIDIRECTIONALLY SWEPT PAST BY THAT EDGEPORTION IN EACH CYCLE OF THE HIGHER-AMPLITUDE VIBRATION OF THE REEDMEANS, CREATING IN THE IMMEDIATE VICINITY OF SAID EDGE PORTION AMAGNETIC FIELD WHICH WHEN SAID CONDUCTOR IS SWEPT PAST BY THE REEDPASSAGES TRANSVERSELY THROUGH SAID CONDUCTOR ALONG THE PLANE OF THEREED, AN ELECTRICALLY CONDUCTIVE LOOP IN WHICH SAID CONDUCTOR ISSERIALLY INCLUDED, AND OUTPUT MEANS RESPONSIVE TO THE CURRENT GENERATEDIN THE LOOP BY THE VIBRATING REED.